Variation and Natural Selection Flashcards

A set of vocabulary flashcards covering variation, adaptive features, natural selection, and selective breeding based on Cambridge CIE IGCSE Biology notes.

Variation

Differences between individuals of the same species.

Phenotypic Variation

The difference in features between individuals of the same species.

Genetic Variation

Differences in features between individuals of the same species that are controlled entirely by genes.

Continuous Variation

Variation in which there are very many small degrees of difference for a particular characteristic between individuals arranged on a continuous scale, producing a smooth bell curve graph.

Discontinuous Variation

Variation in which there are distinct differences for a characteristic without in-between groups, producing a step-like bar graph.

Environmental Variation

Differences in phenotypic features caused by factors outside of the organism, such as climate, diet, culture, lifestyle, and accidents.

Mutation

Random genetic changes to the base sequence of DNA, forming new alleles.

Adaptive Features

Inherited features that help an organism to survive and reproduce in its environment.

Fennec Fox Adaptive Features

Large ears for efficient heat loss and excellent hearing, pale fur for camouflage with sand, and fur on feet for protection from hot sand.

Hydrophytes

Plants adapted to live in extremely wet conditions, featuring large air spaces in leaves for flotation, small roots, and stomata concentrated on the upper epidermis.

Xerophytes

Plants adapted to live in extremely dry conditions, featuring thick waxy cuticles, sunken stomata, small needle-shaped leaves, shallow extensive root systems, and thickened stems for water storage.

Natural Selection

The process in which individuals with adaptive features suited to their environment survive, reproduce, and pass on their advantageous alleles at higher rates.

Survival of the Fittest

A term used to describe how organisms with characteristics suited to their environment succeed in the competitive struggle for survival against other members of their population.

Evolution

The change in adaptive features of a population over time as a result of natural selection.

Antibiotic Resistance Selection

The process where exposure to antibiotics kills non-resistant bacteria, allowing resistant bacteria with reduced competition to multiply and share plasmid-borne resistance genes.

Selective Breeding

The deliberate process where humans select individuals with desirable characteristics and breed them together across successive generations.

Wild Brassica Products

Crop varieties produced by selectively breeding wild brassica: cabbage (terminal bud), cauliflower (flower cluster), broccoli (flowers and stems), Brussels sprouts (lateral buds), kohlrabi (stem), and kale (leaves).

Artificial Selection vs Natural Selection

Artificial selection is human-driven, faster, and selects features useful to humans; natural selection occurs naturally, takes longer, and selects features that improve environmental adaptation and survival.

Causes of Genetic Variation

Mutations in DNA base sequences, meiosis (allele segregation), random mating, and random fertilisation.